The invention is in the field of pipe fittings, specifically pipe elbows and pipe connections.
Most piping installations require changes of direction. With rigid pipe, the change in direction is effected with elbow-type fittings which attach to lengths of straight pipe. Conventional pipe elbows are available in fixed angular increments, typically xe2x85x9 bend increments (90, 45, 22xc2xd degrees). When a pipe layout requires an intermediate angular displacement, the pipe fitter finds himself in a difficult situation.
In some specific situations, provision is made for selecting a specific angular displacement. For example, U.S. Pat. No. 2,654,619 to Guam, describes a reducing elbow for welded pipe, part of which has constant radius of curvature and diameter. The pipe fitter can sever the elbow at the desired point and weld it into his run of pipe. Two cuts are required to be made exactly perpendicular to the axis of curvature to provide a weldable fit to the mating piece of pipe. Williams U.S. Pat. No. 2,449,265 provides a rubber automobile radiator hose which can be cut along lines marked to agree with specific automobile models. The hose depends on its elasticity at the cut end for attachment to the car radiator.
A need therefore exists for a pipe elbow which can be adapted to whatever angular displacement is required for a piping installation, and it is this need which the invention addresses.
In what follows, these terms mean these things:
Proximal means the end of a pipe fitting to be connected to a run of pipe.
Distal refers to the end of a pipe fitting farthest from a run of pipe after it has been joined thereto.
Pipe refers to any rigid conduit with a continuous periphery, whether of round, rectangular, or other shape. For example, rectangular duct work is included in the term xe2x80x9cpipexe2x80x9d.
Dimensions hereunder means the set of dimensions necessary and sufficient to specify the cross-sectional configuration of a piece of pipe. For round pipe, the term refers to its diameter. When a pipe connection is described, clearance between the mating parts is to be understood as implied. The clearances contemplated are the standard industry clearances appropriate to the material used.
Inner aspect means the wall of an arcuate pipe closest to a center of curvature which is the center of a circle of which the wall is an arc segment.
Outer aspect means the wall of an arcuate pipe furthest from a center of curvature which is the center a circle of which the wall is an arc segment.
Arc refers to any curved line and is not limited to being a segment of a perfect circle. An arc associated with a constant radius of curvature is a segment of a circle.
The pipe fitting of the invention comprises two parts, each with a proximal, or upstream end, and a distal, or downstream end. The proximal end of the first elbow part and the distal end of the second elbow part are contemplated to accommodate standard pipes and fittings. The distal end of the first part has a constant radius of curvature which fits into the proximal end of the second elbow part. The second elbow part has the same radius of curvature as the first elbow part. The first elbow part can be precut to a desired included angle and inserted into the proximal end of the second elbow part. An internal stop is provided within the second elbow part. The distal end of the first elbow part is inserted into the second part until it bottoms against or abuts the stop, providing an elbow of fixed included angle. Alternatively, the first part may be inserted into the second part just far enough to provide the included angle which a given run of pipe requires.
The distal end of the first elbow part has an outer surface which has an inner aspect. The inner aspect defines an arc which extends along the entirety of an arcuate segment, from the distal end of the first part to the portion adapted to accommodate standard pipes. Thus, the invention is directed to an elbow having a first part with an extended region of curvature near the proximal end, (i.e. no flattened outer surface along its inner aspect). The proximal end of the second part has an expanded lip which is capable of conformingly fitting with the expanded region of curvature of the first part. Where the application requires that the first elbow part be cut for a very acute angle (as measured off an imaginary line extending from the end of a run of pipe to which the first part is connected), the expanded region of curvature of the first part and the lip of the second part provide for a minimum extension of the first elbow part into the second elbow part in order to meet industry standards for minimum insertion of mating parts.